An asteroid the size of a city block will zoom by Earth inside the orbit of the moon today (Nov. 8), but it poses no danger of smashing into our planet, scientists say.

The asteroid 2005 YU55, which is about 1,300 feet (400 meters) across, will make its closest approach to Earth at 6:28 p.m. EST (2328 GMT) today. At that point, the space rock will be traveling at about 29,000 mph and be about 201,700 miles (324,600 kilometers) from Earth — closer than the moon, which orbits 238,864 miles (384,499 km) from us on average.

The flyby will mark the closest such a big space rock has come to Earth since 1976. But there's no need to scurry down to the basement bunker to await an asteroid impact, researchers say.

"2005 YU55 cannot hit Earth, at least over the interval that we can compute the motion reliably, which extends for several hundred years," research scientist Lance Benner, of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., said in a recent NASA video...